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Sentinel: ability to execute notification scripts.
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@antirez
antirez committed Sep 27, 2012
1 parent f105753 commit 999fe0d
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Showing 2 changed files with 95 additions and 11 deletions.
34 changes: 29 additions & 5 deletions sentinel.conf
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4,15 +4,17 @@
# The port that this sentinel instance will run on
port 26379

# sentinel monitor <name> <ip> <redis-port> <quorum>
# sentinel monitor <master-name> <ip> <redis-port> <quorum>
#
# Tells Sentinel to monitor this slave, and to consider it in O_DOWN
# (Objectively Down) state only if at least <quorum> sentinels agree.
#
# Note: master name should not include special characters or spaces.
# The valid charset is A-z 0-9 and the three characters ".-_".
sentinel monitor mymaster 127.0.0.1 6379 2

# sentinel down-after-milliseconds <mymaster> <milliseconds>
# sentinel down-after-milliseconds <master-name> <milliseconds>
#
# Number of milliseconds the master (or any attached slave or sentinel) should
# be unreachable (as in, not acceptable reply to PING, continuously, for the
# specified period) in order to consider it in S_DOWN state (Subjectively
Expand All @@ -21,18 +23,21 @@ sentinel monitor mymaster 127.0.0.1 6379 2
# Default is 30 seconds.
sentinel down-after-milliseconds mymaster 30000

# sentinel can-failover <mymaster> <yes|no>
# sentinel can-failover <master-name> <yes|no>
#
# Specify if this Sentinel can start the failover for this master.
sentinel can-failover mymaster yes

# sentinel parallel-syncs <mymaster> <numslaves>
# sentinel parallel-syncs <master-name> <numslaves>
#
# How many slaves we can reconfigure to point to the new slave simultaneously
# during the failover. Use a low number if you use the slaves to serve query
# to avoid that all the slaves will be unreachable at about the same
# time while performing the synchronization with the master.
sentinel parallel-syncs mymaster 1

# sentinel failover-timeout <mymaster> <milliseconds>
# sentinel failover-timeout <master-name> <milliseconds>
#
# Specifies the failover timeout in milliseconds. When this time has elapsed
# without any progress in the failover process, it is considered concluded by
# the sentinel even if not all the attached slaves were correctly configured
Expand All @@ -47,3 +52,22 @@ sentinel parallel-syncs mymaster 1
# Default is 15 minutes.
sentinel failover-timeout mymaster 900000

# sentinel notification-script <master-name> <script-path>
#
# Call the specified notification script for any sentienl event that is
# generated in the WARNING level (for instance -sdown, -odown, and so forth).
# This script should notify the system administrator via email, SMS, or any
# other messaging system, that there is something wrong with the monitored
# Redis systems.
#
# The script is called with just two arguments: the first is the event type
# and the second the event description.
#
# The script must be exits and executable in order for sentinel to start if
# this option is provided.
#
# Example:
#
# sentinel notification-script mymaster /var/redis/notify.sh


72 changes: 66 additions & 6 deletions src/sentinel.c
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Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,8 @@
#include <arpa/inet.h>
#include <sys/socket.h>

extern char **environ;

#define REDIS_SENTINEL_PORT 26379

/* ======================== Sentinel global state =========================== */
Expand Down Expand Up @@ -169,7 +171,7 @@ typedef struct sentinelRedisInstance {
struct sentinelRedisInstance *promoted_slave; /* Promoted slave instance. */
/* Scripts executed to notify admin or reconfigure clients: when they
* are set to NULL no script is executed. */
char *notify_script;
char *notification_script;
char *client_reconfig_script;
} sentinelRedisInstance;

Expand Down Expand Up @@ -291,6 +293,7 @@ void sentinelDisconnectInstanceFromContext(const redisAsyncContext *c);
void sentinelKillLink(sentinelRedisInstance *ri, redisAsyncContext *c);
const char *sentinelRedisInstanceTypeStr(sentinelRedisInstance *ri);
void sentinelAbortFailover(sentinelRedisInstance *ri);
void sentinelEvent(int level, char *type, sentinelRedisInstance *ri, const char *fmt, ...);

/* ========================= Dictionary types =============================== */

Expand Down Expand Up @@ -403,7 +406,29 @@ void releaseSentinelAddr(sentinelAddr *sa) {
/* =========================== Events notification ========================== */

void sentinelCallNotificationScript(char *scriptpath, char *type, char *msg) {
/* TODO: implement it. */
pid_t pid = fork();

if (pid == -1) {
/* Parent on error. */
sentinelEvent(REDIS_WARNING,"-notification-script-error",NULL,
"#can't fork: %s",strerror(errno));
return;
} else if (pid == 0) {
/* Child */
char *argv[4];

argv[0] = scriptpath;
argv[1] = type;
argv[2] = msg;
argv[3] = NULL;
execve(scriptpath,argv,environ);
/* If we are here an error occurred. */
sentinelEvent(REDIS_WARNING,"-notification-script-error",NULL,
"#execve(2): %s",strerror(errno));
_exit(1);
} else {
sentinelEvent(REDIS_DEBUG,"+child",NULL,"%ld",(long)pid);
}
}

/* Send an event to log, pub/sub, user notification script.
Expand Down Expand Up @@ -480,8 +505,9 @@ void sentinelEvent(int level, char *type, sentinelRedisInstance *ri,
if (level == REDIS_WARNING && ri != NULL) {
sentinelRedisInstance *master = (ri->flags & SRI_MASTER) ?
ri : ri->master;
if (master->notify_script) {
sentinelCallNotificationScript(master->notify_script,type,msg);
if (master->notification_script) {
sentinelCallNotificationScript(master->notification_script,
type,msg);
}
}
}
Expand Down Expand Up @@ -584,7 +610,7 @@ sentinelRedisInstance *createSentinelRedisInstance(char *name, int flags, char *
ri->failover_start_time = 0;
ri->failover_timeout = SENTINEL_DEFAULT_FAILOVER_TIMEOUT;
ri->promoted_slave = NULL;
ri->notify_script = NULL;
ri->notification_script = NULL;
ri->client_reconfig_script = NULL;

/* Add into the right table. */
Expand All @@ -608,7 +634,7 @@ void releaseSentinelRedisInstance(sentinelRedisInstance *ri) {
/* Free other resources. */
sdsfree(ri->name);
sdsfree(ri->runid);
sdsfree(ri->notify_script);
sdsfree(ri->notification_script);
sdsfree(ri->client_reconfig_script);
sdsfree(ri->slave_master_host);
sdsfree(ri->leader);
Expand Down Expand Up @@ -881,6 +907,21 @@ char *sentinelHandleConfiguration(char **argv, int argc) {
ri = sentinelGetMasterByName(argv[1]);
if (!ri) return "No such master with specified name.";
ri->parallel_syncs = atoi(argv[2]);
} else if (!strcasecmp(argv[0],"notification-script") && argc == 3) {
/* notification-script <name> <path> */
ri = sentinelGetMasterByName(argv[1]);
if (!ri) return "No such master with specified name.";
if (access(argv[2],X_OK) == -1)
return "Notification script seems non existing or non executable.";
ri->notification_script = sdsnew(argv[2]);
} else if (!strcasecmp(argv[0],"client-reconfig-script") && argc == 3) {
/* client-reconfig-script <name> <path> */
ri = sentinelGetMasterByName(argv[1]);
if (!ri) return "No such master with specified name.";
if (access(argv[2],X_OK) == -1)
return "Client reconfiguration script seems non existing or "
"non executable.";
ri->client_reconfig_script = sdsnew(argv[2]);
} else {
return "Unrecognized sentinel configuration statement.";
}
Expand Down Expand Up @@ -2511,8 +2552,27 @@ void sentinelCheckTiltCondition(void) {
sentinel.previous_time = mstime();
}

/* Handle terminated childs resulting from calls to notifications and client
* reconfigurations scripts. */
void sentinelHandleChildren(void) {
int statloc;
pid_t pid;

if ((pid = wait3(&statloc,WNOHANG,NULL)) != 0) {
int exitcode = WEXITSTATUS(statloc);
int bysignal = 0;

if (WIFSIGNALED(statloc)) bysignal = WTERMSIG(statloc);
sentinelEvent(REDIS_DEBUG,"-child",NULL,"%ld %d %d",
(long)pid, exitcode, bysignal);

/* TODO: remove client reconfiguration scripts from the queue. */
}
}

void sentinelTimer(void) {
sentinelCheckTiltCondition();
sentinelHandleDictOfRedisInstances(sentinel.masters);
sentinelHandleChildren();
}

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